I. Field of the Invention
This invention relates generally to a lithotripsy device for breaking stones in the urinary tract or gall bladder, and more particularly to such a device having an elongated flexible stone impacting member designed to be passed through the working lumen of a steerable endoscope for applying a breaking force to renal or gall bladder calculi (stones) to mechanically break them to a size that can be more readily passed.
II. Discussion of the Prior Art
Over the past 15 years or so, the management of renal stones in the urinary tract has undergone radical change. In many instances, in the late 70's, open surgical removal was the principal mode of treatment for urolithiasis and cholecystolithiasis. In about 1980, percutaneous techniques, ureteroscopy and extracorporeal shock wave lithotripsy (ESWL) began to be used by urologists to successfully treat patients with renal calculus (stones). During the 1980's there have been a significant number of technical advances in the use of ESWL. Nonetheless, there still remains a need for endoscopic treatment of ureteral and renal calculi using ureteroscopy or percutaneous nephrolithotripsy, depending upon the location of the stone, its size and composition.
Various methods of endoscopic stone fragmentation have been discussed in the literature. In a paper by Reuter, et al., entitled "Electronic Lithotripsy of Utereal Calculi" published in the Journal of Urology in 1973, there is described an electrohydraulic lithotrite in which a spark induced shock wave travels through a fluid medium to the calculus to be fragmented. Electrohydraulic lithotripsy, however, is considered by some authors to be the most dangerous type to use.
There is also a laser device used in the endoscopic treatment of patients having renal stones. Here, a flexible or semi-rigid endoscope is used to transmit laser energy to the stone to be fragmented. However, it has been found that while laser probes are smaller in diameter and more readily insertable into the urinary tract, they do have difficulty in fragmenting dense, poorly fragile calculi, such as calcium oxalate, monohydrate or cystine stones. Moreover, laser systems tend to be very costly, limiting their availability to major medical centers.
In about 1990, a pneumatically driven lithotrite referred to as the "Swiss Lithoclast" has been used and reported on by a number of urologists. The device in question is more particularly described in the Favre U.S. Pat. No. 5,160,336. It includes an elongated wire having an anvil on one end thereof which acts as a wave guide to transmit shock waves, created by a pneumatically driven bullet-like projectile striking the anvil, to a stone to be fragmented. The wave guide is adapted to be inserted through the working lumen of an endoscope for accurate positioning of the distal end thereof against the stone to be reduced.
There still remains a need for a more efficient endoscopic lithotripsy device for treating difficult stones, which are located in areas of the body that are hard to reach. Such a system must be capable of delivering high energy impacts while still capable of operating within the working lumen of small diameter flexible, steerable endoscopes.
It is accordingly a principal object of the present invention to provide a new and improved endoscopic lithotriptor.
Another object of the invention is to provide an endoscopic lithotriptor having a highly flexible stone impacting member, capable of passing through the lumen of an endoscope such as an ureteroscope or a nephroscope of conventional design.
Still another object of the invention is to provide a lithotriptor device capable of delivering a greater blow to a stone to more effectively fragment the stone.
Yet another object of the invention is to provide an improved pneumatic driven lithotriptor that is relatively small in size and attachable to an endoscope with which it is to be used without detracting from the ability of the urologist to view the site and manipulate the working end of the lithotriptor.